Pubertal development has been linked to both internalizing and externalizing problems in adolescence, including depression, aggressiveness, and delinquency. However, the reasons for this association are not well understood. Recent work on adolescent brain development suggests a possible mediating mechanism}an increase in emotionality associated with the pubertal transition. Pubertal increases in emotionality, if left unchecked by self-regulatory processes, may explain the rise in both depressive symptoms and antisocial behaviors during adolescence. Similarly, emotionality, in combination with self-regulation, has been implicated in the development of prosocial competencies. The long term goal of this research program is to elucidate the processes through which pubertal development influences adolescent behavior problems and prosocial competence. The proposed research is designed to examine these issues through secondary analysis of longitudinal data from the NICHD Study of Early Child Care. We will address the following specific aims: (1) To test a theoretical model linking puberty, emotionality, self-regulation, and psychosocial adjustment concurrently and longitudinally;(2) To test the proposed relations among emotionality, self-regulation and psychosocial adjustment over a more extended period of time (grades 3-6);and (3) To examine the associations between: (a) pubertal growth trajectories and trajectories of psychosocial adjustment;(b) pubertal growth trajectories and change trajectories of emotionality;and (c) change trajectories of emotionality and trajectories of psychosocial adjustment. The proposed project will make significant theoretical and empirical contributions that have important health implications. First, we propose a theoretical model that integrates theories of emotionality, self-regulation, and pubertal development. The model specifies mediating and moderating processes linking pubertal development and adjustment. Furthermore, the research will add to the sparsely investigated links between emotionality and self-regulation in adolescence and between pubertal development and prosocial competencies. Second, these issues will be examined in a relatively large longitudinal data set using multiple methods and sophisticated statistical techniques. And third, the findings are expected to further our understanding of biologically based processes and adjustment in adolescence. These findings will inform the development of more effective intervention programs and policies to enhance adolescent health. Project Narrative The proposed project will make significant theoretical and empirical contributions that have important health implications. We propose a theoretical model that integrates theories of emotionality, self-regulation, and pubertal development and will examine these links using a relatively large longitudinal data set, multiple methods, and sophisticated statistical techniques. These findings will inform the development of more effective intervention programs and policies to enhance adolescent health.